[58.07] The Matter Distribution in Galaxy Clusters

D.J. Sand, T. Treu, R.S. Ellis (Caltech)

One of the basic predictions of the Cold Dark Matter (CDM)
picture of structure formation is that the density profiles
of DM halos are universal in form across a wide range of
mass scales from dwarf galaxies to clusters of galaxies. To
test this prediction at the galaxy cluster scale, we have
developed a method to determine the luminous and dark matter
distribution in the inner regions of clusters with giant
arcs around a central brightest cluster galaxy (BCG) using a
lensing analysis and the velocity dispersion profile of the
BCG to put very tight constraints on the matter density
profile. A search of the entire HST archive for galaxy
clusters with both a dominant, relatively isolated BCG and
nearby giant gravitational arcs suitable for this task has
been completed. Not only has this search yielded well over a
dozen suitable systems, but it has also uncovered many other
possible lensing features (some of which have been confirmed
spectroscopically). Here we will present the results from
the archive search and talk about the first three galaxy
clusters studied in detail: MS2137, R1133, and Abell 383.
All three have both tangential and radial gravitational
arcs, allowing for a very accurate measurement of the
controversial inner slope of dark matter halos, and hence a
stringent test of CDM.

The author(s) of this abstract have provided an email address
for comments about the abstract:
djs@astro.caltech.edu